1. Field of the Invention
The present invention relates generally to the coupling of one vehicle to another vehicle. More particularly, the invention relates to an arrangement for coupling a motor vehicle to another vehicle. The invention will be specifically described hereinafter in the context of coupling a trailer to a truck. However, it is to be appreciated that the invention has broader application than this specific application, and may be used for coupling together other vehicle types.
2. Description of the Prior Art
Road freight transport in Australia and New Zealand, as in other countries and regions of the world, is a vital component of a nation's transport infrastructure. Trucks are used in the transport of a massive variety of goods all over Australia and New Zealand and over a range of distances, including relatively short distances, as well as over longer distances.
Trucks are available in a multitude of types, sizes and cargo capacities, in part to meet the various demands required for the transport of goods.
In general, the transport capacity and versatility of a truck can be increased when used in conjunction with a trailer or other towed vehicle coupled to the rear of the truck in question.
Hereinafter, trailers and other towed vehicles will be collectively referred to as “trailers”. This is not intended in any way to limit the scope of the invention sought in the application.
Like trucks, trailers are available in a large range of types, sizes and cargo capacities.
Towing a trailer behind a truck requires a truck coupling provided at or near the rear of the truck for coupling to a mating component provided on the trailer. There are two common types of couplings used in Australia and New Zealand, these being the Ringfeder® coupling and the Bartlett® ball coupling. Trucks in Australia and New Zealand configured for towing trailers usually include one of these two coupling types, or an equivalent coupling type.
In broad terms, a Ringfeder® coupling is mounted to the rear of a truck and usually includes an opening facing rearwardly of the truck for receiving a towing eye provided at the distal end of a drawbar mounted to and extending forwardly from a trailer. Insertion of the towing eye through the opening causes the eye to contact a coupling bolt of the coupling. The bolt can be manually raised in a vertical direction to allow entry of the towing eye. The bolt can then be lowered through a bolt receiving hole provided in the eye once the hole in the eye aligns with the bolt. A safety device is provided to prevent inadvertent removal of the bolt from the towing eye. The safety device must be disengaged before the truck and trailer can be disconnected.
Generally, Ringfeder® couplings are used for trailers having wheels located at the front and rear of the trailer. During towing, longitudinal and transverse loads are transferred from the truck to the trailer and vice versa through the Ringfeder® coupling. Ringfeder® couplings experience negligible vertical loads as the weight of the trailer is supported evenly by the trailer's wheels. This, in turn, reduces wear on the truck's suspension and reduces the stress experienced by the truck's chassis. Ringfeder® couplings are generally known for their ease of hook-up. In this regard, the coupling bolt is simply raised until the Ringfeder® coupling and towing eye come together, at which time the coupling bolt is lowered and the coupling secured. One drawback of Ringfeder® couplings is that they are generally not designed for supporting substantive vertical loading and so are unsuitable for use with trailers having wheels at the centre or rear of the trailer body.
A Bartlett® ball coupling is configured as a load bearing truck/trailer connection, such that it can accommodate substantive vertical loading. As such, it is used for plant trailers, which only have wheels at the centre or rear of the trailer body. Longitudinal, transverse and vertical loads are each transferred through the Bartlett® ball coupling.
In overall appearance, a Bartlett® ball coupling resembles a conventional car tow bar ball, although it is to be appreciated that a Bartlett® ball coupling is more robust than a conventional tow bar, given the larger loads it is potentially subject to.
Desirably, Bartlett® ball couplings can accommodate load bearing applications, and are substantially free of the backlash and wear encountered in Ringfeder® couplings. Undesirably, however, Bartlett® ball couplings are generally more difficult to couple and uncouple than Ringfeder® couplings.
The versatility of any existing truck fitted with a towing coupling is limited to the extent that the truck is unable to tow trailers fitted with an incompatible coupling. For example, a truck fitted with a Ringfeder® coupling cannot be used to tow a trailer fitted with a Bartlett® ball coupling, even though it may at times be convenient or desirable to do so. Similarly, a truck fitted a Bartlett® ball coupling cannot be used to tow a trailer fitted with a Ringfeder® coupling.
Removing a Ringfeder® coupling and replacing it with a Bartlett® ball coupling (or vice versa) requires several hours of labour and multiple safety checks. This procedure can be potentially dangerous if the correct equipment and safety procedures are not followed. Therefore, it is generally time consuming and otherwise inconvenient to swap the type of coupling fitted to a truck in order to tow a different trailer type.
Moreover, the generally limited coupling mounting locations provided on the rear of a truck make it unfeasible to separately mount both Ringfeder® and Bartlett® ball couplings.
Thus, trucks are generally only capable of towing a certain type of trailer throughout their respective working lives, which is undesirable. It also undesirably increases the presence of trucks on the road and hence raises vehicle emissions.
It would therefore be desirable to provide an arrangement whereby a truck can conveniently tow trailers having different coupling types including, but not limited to a Ringfeder® coupling and a Bartlett® ball coupling.
The above discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the prior date of each claim of this application.